In a conventional bifacial photovoltaic module, a rear-side contact structure 100 (FIG. 1) with Silver solder pads 106 is provided on the rear-side of a substrate 102 for electrically contacting the photovoltaic module. Furthermore, Aluminum contact fingers 104 are provided for collecting the photovoltaic current generated by the photovoltaic module. The Silver solder pads 106 have a lower thickness than the Aluminum contact fingers 104. The contact fingers 104 are configured partially overlapping on the solder pads in order to electrically interconnect these. By this overlapping, an Aluminum bead 108 is configured on the solder pads 106.
Cell connectors 110 are electrically connected to the solder pads 106 in order to electrically interconnect several photovoltaic modules. For this purpose, the cell connectors 110 are soldered on the solder pads 106. For this, it is necessary that a soldered cell connector 110 is bent for soldering on a Silver solder pad 106 over the Aluminum bead 108 in order to be able to contact the Silver surface of the solder pads 106.
In very small solder pads 106, the cell connector 110 cannot be sufficiently bent, so that in this case there is no solder contact. Moreover, the cell connectors 110 are mechanically stressed in the region of the bead 108, which can lead to the breaking of the cell connectors 110. The problem is aggravated if the bead 108 is reinforced in the border region of both structures by an overlap of Silver and Aluminum layers. Therefore, thin cell connectors 110, such as they are used in the so-called Smart-Wire process, cannot be used with a conventional rear-side contact structure so far used or used only with great difficulty.